PSU Powerful Enough for 7900GS KO?

I *finally* bought (well, it was a gift) a nice video card for my system. The power requirements call for a Power Supply of:

400Watts
20A on +12V Rail

I have a PSU of:

450Watts
18A on +12V Rail

My question to you (everyone) is if you think I should try to use the card with this PSU, or should I just buy a nicer one in general. If I get a new Power Supply, what should I get (another question in another post from me)? I know of Thermaltake, and was recently told that FSP Group makes a good PSU as well. Is there any other brand that you would suggest to me? Thank you in advance for any replies .

What brand is your current power supply? That, w/ the other info you gave, will help determine if you need a new one or not.
PC Power and Cooling makes good PSUs, but they are, um, rather expensive (but w/excellent quality). Also, I think some of OCZ's are pretty good.
--kitty

Edit: I just saw your other post where you were describing your card. Nice card!! makes me wish....

You know, you can always get a gfx-dedicated psu too. There was one on newegg, 250W that can handle quad-sli (certified by nvidia). It was from a respectable company too, just forgot which one =/... ~70$ I belive. Just another option.

Oh, my mistake, I in fact forgot to list that my Power Supply is generic (it came with my case), therefore, it is not of brand name status (I forget the actual brand, but I can say it is not known). Personally, I feel that a new PSU will almost be necessary, although I was just asking for people's opinion. Thank you for you inquiries/help !

I prefer that you play it safe and get at least a 500W PSU. I like this one since it's an Antec. I've personally used an Antec PSU and it still works great after 4 years. There might be cheaper options available but I recommend this due to it's exceptional reputation for excellent performance.